Apparatus and method for bonding electronic component, circuit board, and electronic component mounting apparatus

ABSTRACT

Disclosed are an apparatus and a method for bonding electronic components, a circuit board, and an electronic component mounting apparatus, whereby various kinds of circuit boards can be manufactured, each by a small amount, with high productivity as compared with the conventional art. There are provided a stage member and a heating device, so that a circuit board is heated by the heating device while held in contact with the stage member, which stage member has a size almost equal to that of one circuit board. Generation of losses can be reduced for compact circuit boards, and heating can be performed individually, correspondingly, for each kind of circuit board. Manufacturing various kinds of circuit boards, each by a small amount, with high productivity as compared with the conventional art is enabled accordingly.

This application is a divisional of U.S. Ser. No. 10/244,429, filed Sep.17, 2002.

TECHNICAL FIELD

The present invention relates to an apparatus and a method for bondingelectronic components to a circuit board by using a heating source, acircuit board manufactured by the method, and an electronic componentmounting apparatus having a bonder for an electronic component, and moreparticularly, relates to an apparatus and a method for bondingelectronic components so as to manufacture compact and thin circuitboards to be used in compact mobile devices, a circuit boardmanufactured by the method, and an electronic component mountingapparatus.

BACKGROUND OF THE INVENTION

In a liquid crystal module used for a mobile device or the like,electronic components are mounted to a flexible substrate (FPC) so as tocontrol display of a liquid crystal display part and electricallyconnect a liquid crystal module to a mother board. To the FPC aremounted a driver IC for the above display control, and chip componentssuch as capacitors, and the like. Since connection parts of the driverIC have narrow pitches, and contamination of the connection parts causesa decrease of reliability of the liquid crystal module, the driver IC isnormally mounted before the chip components are mounted.

After the driver IC is mounted, as shown in FIG. 19, solder is suppliedonto the FPC by a solder printer 1 and, chip components are mounted ontothe FPC by a component mounting machine 2. Then, the FPC is carried intoa reflow apparatus 3 having a heat source for melting the solder,whereby the solder is melted and the chip components are bonded to theFPC. In this case, if a circuit board has a thickness of approximately 1mm and rigidity, the circuit board can be belt transferred by aconveyor. However, in a case of a flexible and film-shaped circuitboard, e.g., the above FPC, as shown in FIG. 20, a method is employed inwhich FPCs 5 are aligned and fixed on a pallet 4, transferred andcarried into the reflow apparatus 3. The reflow apparatus 3 at this timeis a reflow apparatus which heats an environment in a furnace and thenon the pallet 4, causes soldering operations on the FPCs 5 to beperformed together.

In producing FPCs 5 of different kinds, each kind of FPC 5 on whichcomponents corresponding to each kind are mounted is transferred to thereflow apparatus. But, the reflow apparatus, which heats the environmentin the furnace, has poor productivity in this case, and it is moreefficient to heat only necessary portions. As such, a reflow apparatususing local heating by providing a light beam system as shown in FIG. 21is effective. Particularly for preventing light from being applied toother than necessary portions, an arrangement is effective whereby lightemitted from a light irradiation part 11 is applied only to thenecessary portions through an opening 13 of a mask 12. Reference numeral6, reference numeral 7 and reference numeral 8 in FIG. 21 indicate achip component, IC and solder, respectively.

In producing many FPCs 5 of the same kind, productivity is improved byarranging the FPCs 5 on a pallet 4 as large as possible and executingbonding by solder on the FPCs 5 at a single time. However, there islittle time in many cases, lately from determining specifications of acircuit board, to produce the circuit board because of a short life ofgoods, a variety of kinds, complication of design due to sophisticationof functions, and fluidity of market trends, and consequently a massproduction method by using a large pallet 4 cannot meet enhancingproduction efficiency requirements.

The production equipment indicated in FIG. 19 is based on a condition oftreating large substrates, and therefore each apparatus is itself large.Particularly, the reflow apparatus which heats the environment in thefurnace generally has a length of 3-5 m because of uniform heating, andthe equipment is too large with respect to a circuit board having a sizeof approximately 2-30 mm, thereby obstructing flexible measures. Thesystem with the solder printer 1, the component mounting machine 2 andthe reflow apparatus 3 shown in FIG. 19 has a total length of as longas, e.g., 7 m.

Although the light beam system is effective in a case of components ofthe same kind or a small number of components, the number of chipcomponents 6 and the number of kinds of chip components on an FPC 5 tendto increase these days in accordance with an enhanced level of functionof the liquid crystal module, and therefore, setting an irradiationcondition or the like becomes difficult when there are components havingdifferent light absorptances on the FPC 5. For instance, it is possibleto manipulate a condition of the mask 12 for black electronic componentsor electronic components that are to be slightly heated, but there is alimitation imposed on meeting every component by the mask 12 alonebecause an adjacent solder is half melted or the like.

The present invention is devised to solve the above problems and has forits object to provide an apparatus and a method for bonding electroniccomponents, which enable manufacturing a large number of kinds ofcircuit boards, each by a small amount, with a higher productivity thanin the conventional art, circuit boards manufactured by the method, andan electronic component mounting apparatus having a bonder for anelectronic component.

SUMMARY OF THE INVENTION

In order to accomplish the above objective, the present invention isconstituted as follows.

A bonder for an electronic component of a first aspect of the presentinvention comprises:

-   -   a stage member for having placed thereon a circuit board to have        electronic components mounted thereto; and    -   a heating device for heating the stage member so as to heat the        circuit board held in contact with the stage member, and melt a        bonding material for bonding the electronic components and the        circuit board to each other.

A bonder for an electronic component of a second aspect of the presentinvention comprises:

-   -   a plurality of stage members for having placed thereon a circuit        board to have electronic components mounted thereto; and    -   a heating device provided for each of the stage members for        heating its stage member so as to heat the circuit board held in        contact with this stage member, and melt a bonding material for        bonding the electronic components and the circuit board to each        other.

In the above first and second aspects, there can be provided a suctiondevice connected to the stage member(s) for sucking and holding thecircuit board to the stage member(s).

Also in the first and second aspects, a rear face of each stage memberwhich comes into contact with its respective heating device, and thisheating device, can define a space for suction to allow the stage memberto be sucked by the suction device.

Further in the first and second aspects, each stage member can have anopening for suction which connects the suction device directly to eachstage member.

In the first and second aspects, each stage member can also have asubstrate suction hole for sucking a suction region at a stage membercontact face of the circuit board held in contact with this stagemember, and which connects with the opening for suction.

Yet further in the first and second aspects, there can be provided amember for adhesion to be held between each stage member and itsrespective heating device for adhering the stage member and the heatingdevice to each other, and a suction device for each stage member whichis connected to each heating device for sucking and holding the stagemember to its heating device via the member for adhesion by performing asuction operation.

Still in the first and second aspects, an adhesion member contact faceof each stage member held in contact with its respective member foradhesion, and this member for adhesion, can define a space for suctionto allow the stage member to be sucked by the suction device for thestage member.

In the first and second aspects, each heating device can include aceramic heater and heat the circuit board by changing a heatingtemperature with respect to a heating time.

Again in the first and second aspects, there can be provided a coolingdevice, to be connected to the heating device, for cooling the circuitboard.

In an electronic component bonding method according to a third aspect ofthe present invention, the method comprises:

-   -   heating a circuit board that is to have electronic components        bonded thereto by a bonding material, with the circuit board        being placed on a stage member so as to be in contact therewith,        and    -   melting the bonding material by the heating.

A circuit board of a fourth aspect of the present invention is a circuitboard having electronic components bonded thereto by performing theelectronic component bonding method of the above third aspect.

An electronic component mounting apparatus of a fifth aspect of thepresent invention comprises the bonder for an electronic component ofthe first aspect or the second aspect.

According to the bonder for an electronic component of the first andsecond aspects, the electronic component bonding method of the thirdaspect and the electronic component mounting apparatus of the fifthaspect of the present invention described above, there are provided thestage member(s) and the heating device(s), wherein the circuit board isbrought into contact with the stage member(s) having a size almost equalto a size of one circuit board, and heated by the heating device(s),thus enabling individual heating corresponding to each of various kindsof circuit boards as well as reducing generation of losses with regardto compact circuit boards. Many kinds of circuit boards can bemanufactured, each by a small amount, with a higher productivity ascompared with the conventional art.

In addition, the suction device for sucking and holding the circuitboard to the stage member(s) enables the circuit board to be tightlyadhered to the stage member(s), so that a temperature control of thecircuit board can be carried out more accurately.

Each stage member has the opening for suction which directly connects tothe suction device, thereby preventing bonding material fromcontaminating the heating device(s) when the bonding material is melted.A cleaning operation for each heating device is eliminated and anavailability rate of the bonder for an electronic component can beimproved accordingly.

When there are provided the member(s) for adhesion and the suctiondevice for the stage member(s), the stage member(s) can be sucked andheld to the heating device(s) by suction action of the suction devicefor the stage member. Also, when the member(s) for adhesion arearranged, adhesion of the stage member(s) to the heating device(s) canbe improved at a time of suction and holding.

When the adhesion member(s)' contact face(s) and the member(s) foradhesion have a space for suction, a suction force of the stagemember(s) relative to the heating device(s) can be improved.

When the ceramic heater is used for each heating device, responsivenessto a temperature rise/fall at the heating device can be improved. Inconsequence, heating by an appropriate temperature control is enabledfor each of various kinds of circuit boards. Responsiveness to atemperature change at each heating device can be improved also byincluding the cooling device, thus enabling heating by an appropriatetemperature control for each of various kinds of circuit boards.

Regarding circuit boards having a thickness of not larger than 1 mm, orfilm-shaped circuit boards, these circuit boards have a good temperatureresponsiveness to heating control of the heating device. Therefore,heating by an appropriate temperature control is enabled for each ofvarious kinds of circuit boards.

It can be arranged so that one circuit board is heated by a plurality ofstage members. A change in size of various kinds of circuit boards canbe easily responded to by employing this arrangement, whereby heating byan appropriate temperature control for each of various kinds of circuitboards is enabled.

According to the circuit board of the fourth aspect of the presentinvention, onto which the electronic components are bonded by the bonderof the first and second aspects, the electronic component bonding methodof the third aspect and the electronic component mounting apparatus ofthe fifth aspect, since heating is performed by an appropriatetemperature control corresponding to each kind of board, a bonding stateof electronic components can be made uniform for each kind of board.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects and features of the present invention willbecome apparent from the following description taken in conjunction withpreferred embodiments thereof with reference to attached drawings, inwhich

FIG. 1 is a diagram for explaining structure of a bonder for anelectronic component according to a first embodiment of the presentinvention;

FIG. 2 is a perspective view of a circuit board suitable to be heated bythe bonder shown in FIG. 1;

FIG. 3 is a perspective view of a stage member which constitutes a partof the bonder shown in FIG. 1;

FIG. 4 is a perspective view of a heating device which constitutes apart of the bonder shown in FIG. 1;

FIG. 5 is a graph showing an example of a temperature profile used fortemperature control performed by the bonder shown in FIG. 1;

FIG. 6 is a graph showing another example of a temperature profile usedfor temperature control performed by the bonder shown in FIG. 1;

FIG. 7 is a graph showing a still different example of a temperatureprofile used for temperature control performed by the bonder shown inFIG. 1;

FIG. 8 is a perspective view of a modified example of the bonder shownin FIG. 1;

FIG. 9 is a diagram showing a different modified example of the bondershown in FIG. 1;

FIG. 10 is a perspective view of a heating bonder constituted from thebonder shown in FIG. 1;

FIG. 11 is a perspective view of a mounting system constituted from theheating bonder shown in FIG. 10;

FIG. 12 is the mounting system constituted from the heating bonder shownin FIG. 10 in a different example;

FIG. 13 is a diagram of a different example of a transfer unit fortransferring circuit boards to the bonder shown in FIG. 1;

FIG. 14 is a perspective view of another embodiment of the bonder shownin FIG. 1;

FIG. 15 is a perspective view of a stage member shown in FIG. 14;

FIG. 16 is a sectional view of the bonder shown in FIG. 14;

FIG. 17 is a perspective view of a member for adhesion shown in FIG. 14;

FIG. 18 is a perspective view of a heater part shown in FIG. 14;

FIG. 19 is a perspective view of a conventional component mountingsystem;

FIG. 20 is a diagram showing a state in which FPCs are arranged on apallet when the FPCs are to be treated by a conventional reflowapparatus; and

FIG. 21 is a perspective view showing an apparatus arrangement in a caseof heating only a local region of a circuit board in the conventionalart.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An apparatus for bonding electronic components, a method for bondingelectronic components, a circuit board, and an electronic componentmounting apparatus which are embodiments of the present invention willbe described below with reference to the drawings. The method forbonding electronic components is a method performed by a bonder for anelectronic component, the circuit board is a substrate to whichelectronic components are bonded by the electronic component bondingmethod, and the electronic component mounting apparatus is an apparatusprovided with the bonder. The same parts in each of the drawings aredesignated by the same reference numerals.

In the embodiments below, electronic components are components which areto be surface mounted to a circuit board and are to be bonded to thecircuit board by a bonding material, and correspond to, e.g., chipcomponents 6 and an IC 7 shown in FIG. 2. Although a solder, namely, asolder paste is exemplified because of its workability as the bondingmaterial in the following embodiments, the bonding material is notlimited to this and can be, for example, a silver paste, a conductiveadhesive or the like. Also, while a film-shaped flexible substrate,i.e., FPC is adopted as an example of the circuit board in the followingembodiments, the circuit board is not limited to this and may be, e.g.,a substrate having a thickness of at most 1 mm. Moreover, it does notmatter whether or not the circuit board has flexibility. In other words,the circuit board corresponds to one that is produced in a small amountfor every different kind, without being produced in a large amount ofthe same kind as in the conventional art.

First Embodiment;

FIGS. 1-4 show a bonder 101 for an electronic component of the presentembodiment. FIG. 2 shows FPC 5 which corresponds to a circuit board tobe treated by the bonder 101. The FPC 5 is a substrate, for instance,for connecting a liquid crystal module and a motherboard to each other,and is a single-sided mounting substrate. In addition to the IC 7, aplurality of chip components 6 are placed at locations of a componentmounting face 5 a of the FPC 5 where a solder paste 8, not yetsolidified, is applied. In the present embodiment, the IC 7 is alreadymounted to the FPC 5 before the FPC is sent into the bonder 101.

The bonder 01 has a stage member 110 for having placed thereon theabove-described FPC 5, and a heating device 120 for heating the stagemember 10 and thereby heating the FPC 5 held in contact with the stagemember 110, and for melting the solder paste 8 for bonding electroniccomponents 6 to the FPC 5.

The stage member 110 has both a function of receiving and holding theFPC 5 and a function of transmitting heat to the FPC 5, and is easilyreplaceable relative to the heating device 120 so as to meet variouskinds of circuit boards. The stage member 110 is preferably formed of amaterial having a good thermal conductivity such as aluminum, copper,magnesium or ceramic, and has a thickness of approximately 0.5 mm-5 mm.Using aluminum material having a thickness of approximately 2 mm isparticularly preferable because it is inexpensive and can have equalproperties in terms of heat (soaking properties). The stage member 110is a 35 mm×35 mm square corresponding to a size of the FPC 5 to betreated in the present embodiment.

Referring further to FIG. 3, suction holes 111 for adhering the FPC 5are opened to a front face 110 a of the stage member 110 to which a rearface 5 b, opposite to the component mounting face 5 a of the FPC 5, isto be brought into contact. Although there are a plurality of suctionholes 111 arranged in the embodiment as indicated in the drawing foradhering a peripheral edge part of the FPC 5, the number and position ofthe suction holes 111 are determined in correspondence to a circuitboard to be held. Moreover, the suction holes 111 are connected to eachother by suction grooves 112 for the substrate. In addition, suctiongrooves 113 for the stage member are arranged on a rear face 110 b,opposite to a front face 110 a of the stage member 110, for tightlyadhering the stage member 110 itself to a heater part 121 to bedescribed later.

The heating device 120 has the heater part 121, a thermal insulatingpart 122, a base part 123 and a power supply part 124. The thermalinsulating part 122 and the heater part 121 are stacked in this orderonto the base part 123, and the stage member 110 is arranged on theheater part 121.

The heater part 121 is comprised of a so-called ceramic heater, which isheated when a current is supplied from the power supply part 124 to aheater wire of the ceramic heater. In a case of a heater other than aceramic heater, namely, a constant heating heater, responsiveness to atemperature rise/drop is required to be several tens of seconds toseveral minutes, which is poorly productive and impractical. On theother hand, the ceramic heater can respond even within one second orshorter, thereby enabling setting a temperature profile as will bedescribed below.

A temperature of the heater part 121 is measured by a temperaturesensor, for example, a thermocouple 125 disposed inside the heater part121, and is sent to a controller 180. The power supply part 124 isconnected to the controller 180. The controller 180 feedback controlsthe temperature of the heater part 121 on the basis of temperatureinformation supplied from the thermocouple 125 and a preliminarily settemperature profile for controlling a temperature of the circuit board.As shown in FIG. 4, to a stage member set face 121 a of the heater part121, there are opened a hole 133, for adhering the circuit board, tocommunicate with suction grooves 112 arranged in the stage member 110,and moreover, holes 134, for adhering the stage member, to communicatewith the suction grooves 113 formed in the stage member 110. A space forsuction is defined by the suction grooves 113 and the holes 134.

The thermal insulating part 122 is for efficiently transmitting heat ofthe heater part 121 to the FPC 5, and is fixed to the base part 123.

To the base part 123 are connected a suction device 131, for the circuitboard, for adhering the FPC 5 to the stage member 110, and a suctiondevice 132, for the stage member, for adhering the stage member 110 tothe heater part 121. The suction device 131 is connected to the hole 133of the heater part 121 to suck and hold the circuit board, i.e., the FPC5 in this example, to the front face 110 a of the stage member 110 viathe suction grooves 112 and the suction holes 111 through a suctionoperation of the suction device 131. The suction device 132 is connectedto the holes 134 of the heater part 121 to suck and hold the stagemember 110 to the stage member set face 121 a of the heater part 121through a suction operation of the suction device 132. Although the FPC5 and the stage member 110 are sucked and held by separate suctiondevices 131 and 132, respectively, in the present embodiment asdescribed hereinabove, both may be sucked and held by one suctiondevice.

Further, a cooling device 141 for the heater part 121 is connected tothe base part 123 so that the heater part can be forcibly cooled inorder to perform a temperature control conforming to the abovetemperature profile. In this embodiment, the cooling device 141 forciblycools the heater part 121 by supplying a gas, e.g., air to an upper faceor a lower face of the heater part 121. While the thermal insulatingpart 122 is arranged at a lower part of the heater part 121, a coolingdevice 142, for the base part, for cooling the base part 123 isconnected to the base part 123 to prevent the base part 123 from beingheated by a continuous heating operation. The cooling device 142 alikesupplies a gas, for example, air in the embodiment.

Each of the suction device 131 for the circuit board, the suction device132 for the stage member, the cooling device 141 for the heater part andthe cooling device 142 for the base part is connected to the controller180 and controlled in operation.

For the above temperature profile, for instance, such forms as shown inFIGS. 5-7 can be considered. An optimum temperature profile is selectedin accordance with each of parameters, e.g., a type of bonding material,a type and number of electronic components to be bonded onto a circuitboard, and a material, a thickness, and the like of the circuit board.As a selection method, a method conceivable by those skilled in the artcan be employed, such as a method of storing each kind of temperatureprofile corresponding to each of the above parameters in a storage part181 in the controller 180, and automatically extracting the optimumtemperature profile by the controller 180 by inputting informationrelated to the circuit board and electronic components to be treated, ora method of inputting a temperature profile selected by a worker, or thelike.

By way of example, in FIGS. 5-7, a0 represents a room temperature, a1represents a melting point of bonding material, which is a eutecticsolder in the embodiment, and therefore 183° C., a2 represents 230° C.,b1 represents 150° C., b2 represents 220° C., t1 represents one second,t2 represents three seconds, t3 represents four seconds, t4 representsten seconds, and t5 represents six seconds.

In a case particularly where electronic components 6 and 7 have alimitation to heating, a heating temperature can be set to not higherthan the above a2 as an upper limit of the heating temperature. Sincethe FPC 5 is heated only from the rear face 5 b where components are notmounted, the electronic components 6 and 7 are heated eventually.Setting the heating temperature as above is effective also from thispoint of view if in the presence of the above heating limitation.

When it is necessary to suppress generation of a solder ball at amelting time of the solder, as shown in FIG. 5, it is preferable to seta preheating operation of maintaining the same temperature from a timepoint t1 to a time point t2. On the other hand, if an effect of a solderball is negligible because electronic components are relatively large,as shown in FIG. 6, the solder may be melted at a time without settingthe above preheating operation. Meanwhile, if it is desired to shorten atime required for melting the solder and bonding electronic componentsto a circuit board, as shown in FIG. 7, a method is possible in which aheating operation is started preliminarily from preheating temperatureb1, and the temperature b1 is maintained even after completion of solderbonding.

With respect to the above-constituted bonder t 101, an operation of thebonder 101, that is, an electronic component bonding method will bedescribed below. The electronic component bonding method, in other wordsa reflow method, is a method particularly effective for thin circuitsboards, preferably for substrates having a thickness of not larger than1 mm as a standard. Especially as in the present embodiment, the methodis more effective for film-shaped circuit boards, i.e., the above FPC 5because of its good follow-up performance to a temperature control. As amaterial of the circuit boards, a glass fabric based epoxy resin or apaper based phenolic resin is preferred for the 1 mm thick or thinnercircuit boards, and polyimide is preferably used for the film-shapedcircuit boards, because such material has both a strength and a heatresistance in spite of a considerably small thickness of approximately0.01-0.1 mm.

First, the stage member 110 having the suction holes 111 arrangedcorrespondingly to a circuit board, i.e., the FPC 5 in the embodiment,is placed on the stage member set face 121 a of the heater part 121. Thesuction device 132 for the stage member is activated, thereby suckingthe stage member 110 via the holes 134 which are opened to the heaterpart 121, and tightly adhering and fixing the stage member 110 to theheater part 121. Then, after the suction device 131 for the circuitboard is activated, the FPC 5 is placed on the front face 110 a of thestage member 110, and the FPC 5 is adhered and fixed to the front face110 a via the hole 133 of the heater part 121 and the suction holes 111of the stage member 110. As a result, the stage member 110 is tightlyadhered and fixed to the heater part 121, and moreover, the FPC 5 istightly adhered and retained tracing the front face 110 a of the stagemember 110, so that heat of the heater part 121 is efficientlytransmitted to the FPC 5. A heating operation of the heater part 121 iscontrolled by the controller 180 according to the above-describedtemperature profile, whereby solder 8 is melted and electroniccomponents 6 are bonded onto the FPC 5 by the solder. After bonding,operation of the suction device 131 is stopped to stop suction and theFPC 5 is separated from the stage member 110.

According to the bonder 101, one circuit board to be heated is heated bythe heating device 120 while the circuit board is kept in contact withthe stage member 110 having a size nearly equal to the size of thecircuit board. Therefore, generation of losses associated with smallcircuit boards can be reduced, and at the same time, heating can beperformed individually, correspondingly, for each kind of circuit board.It becomes possible to manufacture various kinds of circuit boards, eachby a small amount, with a higher productivity as compared with theconventional art.

Since a circuit board to be heated is heated by the heating device 120while being held in contact with the stage member 110 that is nearlyequal in size to that of the circuit board, a reflow apparatus of anambience circulation type as in the conventional art is eliminated. Itis possible to constitute each bonder 101 of a size of, e.g., 35 mm×35mm for FPC 5 having a size of, e.g., 35 mm×35 mm. A considerably compactapparatus for heating and bonding circuit boards, as compared with theconventional art, is provided accordingly.

In the bonder 101 of the above-discussed embodiment, one FPC 5 is placedon the front face 110 a of the stage member 110 which has a size equalto or slightly larger than that of the FPC 5. However, the size of thecircuit board relative to the stage member 110 is not limited to thisexample of the embodiment. For instance, a plurality of bonders 101 canbe arranged side by side in a lateral direction like a bonder 102 for anelectronic component as shown in FIG. 8, and one circuit board may beplaced on a plurality of stage members 110. An arrangement direction isnot limited to a lateral direction and can be a longitudinal direction,or furthermore, both longitudinal and lateral directions. Also, aplurality of FPCs 5 may be placed on the front face 110 a of one stagemember 110.

By constituting as above, the bonder 101 of the present embodimentbecomes applicable irrespective of the size of circuit boards. The abovestructure of a parallel arrangement is an effective measure when it istaken into account that a large ceramic heater itself is rare atpresent, and development costs for a large ceramic heater is enormous.

By adopting the above structure of the parallel arrangement, it alsobecomes possible to perform one heating control for an entire range of aheating region at one circuit board, or perform mutually differentheating controls for a plurality of areas in a heating region of onecircuit board. More versatility can be provided.

When it is necessary to change a heating condition for a circuit boardmore locally, such an arrangement as a bonder 103 for an electroniccomponent as shown in FIG. 9 is possible in which light beams, laser,hot air or the like is irradiated from above circuit board 5. In FIGS. 8and 9 referred to above, power supply part 124, suction device 131 forthe circuit board, suction device 132 for the stage member, coolingdevice 141 for the heater part, cooling device 142 for the base part,and controller 180 are omitted from the illustration because they can beconstrued as similar to that as shown in FIG. 1.

Second Embodiment;

-   -   An electronic component mounting apparatus (described also as a        “mounting system”) including the bonder 101 will be depicted        next. The foregoing FPC 5 is employed as an example of a circuit        board.

Mounting system 201 shown in FIG. 11 includes a solder supplyingapparatus 210 for applying solder paste 8 to the FPC 5, a componentsetting apparatus 220 for mounting chip components 6 onto the FPC 5, anda heating bonder 230 having the bonder 101 for bonding chip components 6to the FPC 5 by melting the solder paste 8. These are aligned so thatthe FPC 5 is transferred sequentially from the solder supplyingapparatus 210 to the component setting apparatus 220 to the heatingbonder 230. The FPC 5 having IC 7 mounted beforehand is supplied to thesolder supplying apparatus 210. The solder supplying apparatus 210 maybe constructed as either one of a solder printer and a solder dispenser.

As depicted in the foregoing description of the bonder 101, the bonder101 is constituted to heat a circuit board by sucking the circuit boardonto the stage member 110, and at the same time, the stage member 110 ismade to correspond in size to that of the circuit board. Therefore, anarea occupied by the heating bonder 230 is considerably small ascompared with a conventional reflow apparatus. A total length I of themounting system 201 can be kept to, e.g., approximately 2.5 m in thisexample.

The heating bonder 230 will be described with reference to FIG. 10.

The heating bonder 230 has a heating part 235 with bonders 101, acarry-in unit 231 for carrying the FPC 5 into the heating bonder 230from the component setting apparatus 220 of a previous stage, acarry-out unit 233 for sending the FPC 5 out of the heating bonder 230to a next process, a transfer unit 232 for transferring the FPC 5 fromthe carry-in unit 231 to the heating part 235 and from the heating part235 to the carry-out unit 233, and a control unit (controller) 236 forcontrolling operation of these constituting parts.

The carry-in unit 231 has a carry-in stage 2312 which sucks and holdsthe FPC 5 and is reciprocated by a driving device 2311 in an X-directionas a transfer direction. Operation of the carry-in unit 231 iscontrolled by the controller 236. The carry-out unit 233 has a carry-outstage 2332 which sucks and holds the FPC 5 and is reciprocated by adriving device 2331 in the X-direction. Operation of the carry-out unit233 is controlled by the controller 236.

The heating part 235 is constituted of two stages, a first stage 235-1and a second stage 235-2. Each of the first stage 235-1 and the secondstage 235-2 is constituted of two bonders 101, of FIG. 1, arranged in alongitudinal direction, i.e., a Y-direction as indicated in FIG. 10.Therefore, a total of four bonders 101 are used for the heating part235, because one sheet of the FPC 5 to be treated by this mountingsystem 201 corresponds to a size of two stage members 110 of the bonder101 arranged in the Y-direction. A specific size of the FPC 5 to betreated by the mounting system 201 is 35 mm×70 mm. A size of the abovestages is not limited by the form of the mounting system 201 and can bedetermined in accordance with sizes of the circuit boards to be treated.Also, the number of the stages arranged at the heating part 235 is notlimited to this example and can be one or more, which is determined onthe basis of a throughput required for the mounting system.

In FIG. 10, power supply part 124, suction device 131 for the circuitboard, suction device 132 for the stage member, cooling device 141 forthe heater part and cooling device 142 for the base part provided foreach of the bonders 101, which constitute the stages 235-1 and 235-2,are not illustrated because these parts can be construed as equal tothose in FIG. 1, while the foregoing controller 180 is replaced with thecontroller 236. The same temperature control, as the above-describedtemperature control for the bonder 101 by the controller 180, isexecuted for each of the first stage 235-1 and the second stage 235-2 bycontrolling operation thereof by the controller 236.

The transfer unit 232 has a transfer suction device 2321 fortransferring the FPC 5 to the first stage 235-1 and to the second stage235-2 of the heating part 235 from the carry-in stage 2312 of thecarry-in unit 231, a transfer suction device 2322 for transferring theFPC 5 to the carry-out stage 2332 of the carry-out unit 233 from thefirst stage 235-1 and the second stage 235-2, a Z-driving device 2324for moving a transfer arm 2323 having the transfer suction device 2321and the transfer suction device 2322 arranged thereon in a Z-directionwhich is a thickness direction of the FPC 5 and orthogonal to theX-direction and Y-direction, a Y-driving device 2325 for moving theZ-driving device 2324 in the Y-direction, and an X-driving device 2326for moving the Y-driving device 2325 in the X-direction. A suctiondevice omitted from the illustration is included in the transfer suctiondevice 2321 and the transfer suction device 2322. The transfer unit 232constituted as above is controlled to be operated by the controller 236.

Furthermore, the heating bonder 230 has a suction device 234 having aduct 2341 for sucking fumes generated from the FPC 5 being heated by theheating part 235.

Operation of the thus constituted mounting system 201, primarilyoperation at the heating bonder 230 will be described below.

A first FPC 5 transferred from the component setting apparatus 220 issupplied onto the carry-in stage 2312 of the carry-in unit 231 providedas part of the heating bonder 230. Each of the X-driving device 2326,the Y-driving device 2325, the Z-driving device 2324 and the transfersuction device 2321 provided as parts of the transfer unit 232 isdriven, whereby the FPC 5 is sucked and held by the transfer suctiondevice 2321, placed on the first stage 235-1 of the heating part 235,and sucked and held. The FPC 5, while being retained on the first stage235-1, is heated on the basis of a temperature profile by heating device120, that is, is passed through a reflow operation. Fumes generatedduring this heating are sucked by the duct 2341 of the suction device234.

A second FPC 5 carried next into the heating bonder 230 is treatedsimilarly to the above first FPC 5. The second FPC 5 is supplied to thesecond stage 235-2 vacant at present, heated, and temperaturecontrolled, when the first FPC 5 and chip components 6 are bonded toeach other. A succeeding third FPC 5, which has been sucked by thetransfer suction 231, is supplied to the first stage 235-1 and heatedimmediately after the first FPC 5 is completely heated at the firststage 235-1 and removed, by the transfer suction device 2322 of thetransfer unit 232 to the carry-out stage 2332 of the carry-out unit 233,from the first stage 235-1.

The FPC 5 placed and sucked on the carry-out stage 2332 is held andcarried out to a next process. The above operation is repeated, wherebythe FPCs 5 are treated sequentially.

According to the mounting system 201 having the heating bonder 230,since the heating bonder 230 is constituted to be greatly compacted incomparison with the conventional art as described hereinabove, themounting system 201 can be made compact as a whole as compared with theconventional art.

Although the above mounting system 201 is constituted of the soldersupplying apparatus 210, the component setting apparatus 220 and theheating bonder 230 arranged in an array along a transfer direction ofcircuit boards, namely, along the X-direction as shown in FIG. 11, anentire configuration of the mounting system is not limited to the aboveform, and it is possible to construct a mounting system 250 of a rotarytype as shown in FIG. 12.

A circular rotary table 257, with working parts 258 arranged at constantintervals to a circumferential edge part, is installed to beintermittently rotatable relative to a central part of the mountingsystem 250. There are arranged surrounding the rotary table 257 andcorresponding to stop positions of the working parts 258, a soldersupplying apparatus 261 for supplying solder to a circuit board, acomponent setting apparatus 262 for mounting chip components 6 to thecircuit board with the solder supplied thereto, and a heating bonder 263having the above-described bonder 101 for heating the solder and bondingthe chip components 6 to the circuit board. Moreover, a controller 256is provided which is in charge of controlling operation of the mountingsystem 250 in its entirety. Also, there are provided a carry-in unit 251for carrying in a circuit board from a previous process to the mountingsystem 250, a carry-out unit 253 for carrying out a circuit board fromthe mounting system 250 to a next process, and a transfer unit 252 fortransferring circuit boards to the working parts 258. A suction deviceis also disposed for sucking fumes generated during heating of thecircuit boards.

The mounting system 250 constituted as above operates in the followingmanner.

A circuit board is placed on a working part 258 by the transfer unit 252via the carry-in unit 251, and is transferred to the solder supplyingapparatus 261 by rotation of the rotary table 257. Solder is supplied tothe circuit board at the solder supplying apparatus 261. The rotarytable 257 rotates again, so that the circuit board is transferred to thecomponent setting apparatus 262. At the component setting apparatus 262,chip components 6 are mounted onto the circuit board with the soldersupplied thereto. The rotary table 257 rotates again and the circuitboard is transferred to the heating bonder 263. The circuit board isheated and components are bonded to the circuit board at the heatingbonder 263. The circuit board is transferred to the carry-out unit 253by rotation of the rotary table 257 again, and moved by the transferunit 252 to the carry-out unit 253. The carry-out unit 253 carries outthe circuit board to a next process.

For instance, when a first circuit board is being heated by the heatingbonder 263, components are mounted onto a second circuit board by thecomponent setting apparatus 262 and solder is supplied to a thirdcircuit board by the solder supplying apparatus 261. Different processesare thus carried out for a plurality of circuit boards, respectively.

A lateral width of the mounting system can be further reduced byadopting a form with the rotary table 257 as described above with regardto mounting system 250.

When there are eight stop positions arranged at the rotary table 257, arecognition camera for inspecting a supply state of solder to a circuitboard, or a device for adding solder to a part where solder is not fullysupplied, can be installed additionally between the solder supplyingapparatus 261 and the component setting apparatus 262, and effectivelyutilized. The heating bonder 263 can be arranged within a working part258, attached to the carry-out unit 253, or between the rotary table 257and the carry-out unit 253.

In each of the above-discussed embodiments, since the FPC 5 is employedas an example of the circuit board, a method of sucking and holdingcircuit boards is adopted for transferring the circuit board. However,in a case where the circuit board is a substrate which is, e.g.,approximately 1 mm thick and resistant to deformation such as deflectionand the like, such an arrangement as shown in FIG. 13 may be provided inwhich a circuit board 310 is transferred by transfer rails 302 supportedby brackets 301. In this case, while heating bonder 120 is tightlyadhered by an up-down driving part 303 to the circuit board 310, aretaining member 304 is preferably disposed on each transfer rail 302for stabilizing this adhesion.

Third Embodiment;

As is described hereinabove, in the bonder 101 used in each embodiment,the FPC 5 is sucked and held to the front face 110 a of the stage member110 by a suction operation performed by the suction device 131. Apassage for suction passes through the heater part 121 to reach thesuction device 131 as shown in FIG. 4. Therefore, there is a possibilitythat a part of fumes generated, when the FPC 5 sucked to the stagemember 110 is heated and the solder paste 8 is melted, enters the heaterpart 121 due to the above suction. Moreover, there is a type of circuitboard, among circuit boards to be sucked to the stage member 110,through which holes are formed penetrating the board along a thicknessdirection of the board. An amount of fumes passing the heater part 121increases greatly in circuit boards having such through holes.

Entrance of fumes into the heater part 121 necessitates cleaning of theheater part 121, thereby forcing equipment to stop for cleaning work tobe performed, which results in a decrease of productivity.

A bonder for an electronic component according to a third embodiment tobe described below is an improved type of bonder 101 of the above firstembodiment, which is intended for improving productivity by preventingeffects of fumes. The mounting system 201 discussed in the secondembodiment can adopt a configuration provided with a bonder of thefollowing third embodiment in place of the bonder 101.

A flexible substrate (FPC) 405 shown in FIG. 14 is a substrate forconnecting, e.g., a liquid crystal module and a motherboard to eachother, similar to the above-described FPC 5. The flexible substrate is asingle-sided mounting substrate and has a plurality of electroniccomponents 6 and an IC 7 placed on portions of an electronic componentmounting face 405 a of the FPC 405 where solder paste 8, not yetsolidified, is applied. In this embodiment, a plurality of through holes404 are formed penetrating the FPC 405 in a thickness direction of theFPC 405. A recessed part 405 c with approximately a thickness of awiring line, shown in FIG. 16, is formed at a part on a stage membercontact face 405 b of the FPC 405 opposite to the component mountingface 405 a, i.e. the part corresponding to a part without a wiring line.The above through holes 404 are provided for a purpose of disconnectingan unnecessary wiring part, and therefore, the through holes 404 and therecessed part 405 c are normally in a structure in which the holes andthe recessed part are connected to each other.

As indicated in FIG. 14, bonder 401 for an electronic component in thethird embodiment has a stage member 410 for receiving the FPC 405, and aheating device 420 for heating the stage member 410 and thereby heatingthe FPC 405 maintained in contact with the stage member 410, therebymelting the solder paste 8 for bonding components to the FPC 405. Amember 450 for adhesion is preferably arranged between the stage member410 and the heating device 420.

The stage member 410 shown in FIG. 15 is a member corresponding to theearlier described stage member 110, having both a function of receivingand holding the FPC 405 and a function of transmitting heat to the FPC405. The stage member 410 is easily replaceable so as to be able to meetvarious kinds of circuit boards. The stage member 410 is preferablyformed of a material having a superior thermal conductivity such asaluminum, copper, magnesium, ceramic, or the like. Particularly, usingan aluminum member having a thickness of approximately 3 mm is preferredbecause it is inexpensive and exerts soaking properties. In the presentembodiment, the stage member 410 is formed of a 45 mm×80 mm rectangularplate material corresponding to a size of the FPC 405 to be treated.

Moreover, a plurality of substrate suction holes 411 for sucking andholding the FPC 405 are opened to a circuit board placing face 410 a ofthe stage member 410 to which the stage member contact face 405 b of theFPC 405 comes into contact. In the embodiment, as shown in FIG. 16, thesubstrate suction holes 411 are disposed at positions where the holesare prevented from communicating directly with the through holes 404formed in the FPC 405. In addition, the substrate suction holes 411 aredisposed at positions where the holes are prevented from connecting withrecessed part 405 c of the stage member contact face 405 b of the FPC405. So long as these arrangement conditions are satisfied, the numberand arrangement position of the substrate suction holes 411 can bedetermined in accordance with a circuit board to be held. Therefore, thesubstrate suction holes 411 suck a suction region 405 d, other than therecessed part 405 c and the through holes 404, at the stage membercontact face 405 b. The suction region 405 d is normally a flat face butcan be dented.

The substrate suction holes 411 are connected with each other viasubstrate suction grooves 412 formed in an adhesion member contact face410 b of the stage member 410, and each substrate suction groove 412 isconnected to an opening 415 for suction formed in a side face 410 c ofthe stage member 410. The opening 415 for suction is connected directlyto a suction device 431 for the circuit board. Therefore, the FPC 405placed on the substrate placing face 410 a of the stage member 410 issucked and held to the substrate placing face 410 a by a suctionoperation performed by the suction device 431. Although fumes generatedfrom solder paste 8, when components 6 are bonded, possibly enter thesubstrate suction holes 411 and the substrate suction grooves 412through the through holes 404, the fumes are sucked via the opening 415by the suction device 431. The fumes are accordingly prevented frompassing the heating device in the third embodiment.

Since the through holes 404 and the substrate suction holes 411 are notdirectly connected with each other, and since the substrate suctionholes 411 suck the suction region 405 d as described above, a holdingforce for holding the FPC 405 to the substrate placing face 410 a viathe substrate suction holes 411 is large, and holding accuracy can beimproved. Moreover, since the FPC 405 is held to the substrate placingface 410 a through local suction via the substrate suction holes 411, anamount of air leaked can be reduced in comparison with a case of suckingthrough suction holes arranged, e.g., like slots in the substrateplacing face 410 a. Holding accuracy for the FPC 405 to the substrateplacing face 410 a is improved also from this point of view.

In the adhesion member contact face 410 b of the stage member 410 aredisposed suction grooves 413, for the stage member, separately from thesubstrate suction grooves 412 to adhere and hold the stage member 410 tothe heater part 421 via member for adhesion 450. The suction grooves 413for the stage member are circular recesses in the present embodiment asillustrated, each having a diameter larger than a diameter of a passage422, for sucking the stage member, which is formed in a heater part 422to be described later.

As shown in FIG. 17, the member 450 for adhesion is a sheet-like memberhaving both a function of blocking contamination of the stage member 410from reaching the heater part 421 and a function of transmitting heat tothe stage member 410, and is constituted to be easily replaceable toimprove maintenance efficiency. The member 450 for adhesion ispreferably formed of a material having a good thermal conductivity suchas aluminum, copper, magnesium, ceramic, or the like. It is preferableto use particularly an aluminum material having a thickness ofapproximately 0.05 mm because it is inexpensive and soaking propertiescan be obtained. In the embodiment, the member 450 for adhesion is madeof a 45 mm×80 mm rectangle corresponding to a size of the FPC 405 to betreated. As indicated in the drawing, there are formed in the member 450for adhesion, stage member suction holes 451 penetrating in a thicknessdirection of the member 450 for adhesion at the same position and beingof the same shape as the suction grooves 413 for the stage member, whichare present in the adhesion member contact face 410 b of the stagemember 410. A space for suction is constituted by the suction grooves413 and the suction holes 451.

By providing the above member 450 for adhesion, adhesion between thestage member 410 and the heater part 421 described below is improved,and at the same time, the substrate suction grooves 412 of the stagemember 410 are prevented from directly coming into contact with theheater part 421, so that fumes can be prevented from adhering to theheater part 421.

The heater part 421 shown in FIG. 18 is comprised of a ceramic heaterhaving a superior responsiveness to a temperature rise/drop, which isdesigned to be heated when a current is supplied to a heater wire from apower supply part 424. The heating device 420 is constituted of theabove heater part 421 and power supply part 424. In the presentembodiment, the heater part 421 is preferably formed, in a thickness ofapproximately 0.5 mm to 5 mm, of a material having superior soakingproperties and thermal conductivity such as a silicon nitride ceramic,cordierite, aluminum nitride ceramic or the like. Particularly, asilicon nitride ceramic material having a thickness of approximately 2mm is used, because it is preferable since the heater part is madeinexpensive and can exert soaking properties. The heater part 421 in theembodiment is rendered as a 55 mm×90 mm rectangle corresponding to asize of the FPC 405 to be treated. Further, the heater part 421 haspassages 422, for sucking the stage member, formed at a positioncorresponding to the stage member suction holes 451 of the member 450.The passages 422 penetrate the heater part 421 in a thickness directionof the heater part 421. A suction device 432 for the stage member isconnected to the passages 422. Therefore, air of the passages 422, thesuction holes 451 and the suction grooves 413 is sucked by activatingthe suction device 432, whereby the stage member 410 is adhered andsucked to a placing face 421 a of the heater part 421 via the member450.

Although the passages 422 for sucking the stage member are cylindricalpassages in the embodiment, a diameter of each passage is made small incomparison with the above suction holes 413 for the stage member, andthe stage member suction holes 451. By so constituting as above, a spacefor suction, that is, the suction grooves 413 for the stage member canbe secured larger at the stage member 410 with respect to the passages422, and a holding force for holding the stage member 410 to the heaterpart 421 can be improved.

A temperature of the heater part 421 is measured by a temperaturesensor, for example, by a thermocouple 425 installed in the heater part421, and sent out to the controller 480. The power supply part 424 isconnected to controller 480, and the controller 480 feedback controlsthe temperature of the heater part 421 on the basis of temperatureinformation supplied from the thermocouple 425 and a temperature profilepreliminarily set for controlling a temperature of a circuit board. Acooling device 441 for the heater part is connected to the heater part421 so that the heater part 421 can be forcibly cooled to execute atemperature control conforming to the temperature profile. The coolingdevice 441 for the heater part supplies a gas, e.g., air to the heaterpart 421, thereby forcibly cooling the heater part 121 in the presentembodiment.

The controller 480 is connected to the above suction device 431 for thecircuit board, the suction device 432 for the stage member, the powersupply part 424 and the cooling device 441 for the heater part, therebycontrolling operation of each of these parts according to a programstored in a storage part 481.

With respect to the bonder 401 constituted as described hereinabove,operation of the bonder, i.e., an electronic component bonding methodwill be described below. The bonder 401 is particularly effective forheating and holding thin circuit boards, similar to the earlierdescribed bonder 101, and is suitable for substrates having a thicknessof not larger than 1 mm as a guideline.

The member 450 for adhesion is placed on the placing face 421 a of theheater part 421 while the stage member suction holes 451 of the member450 for adhesion are made to correspond to the passages 422 of theheater part 421. Moreover, the stage member 410 is placed on the member450 while the suction grooves 413 of the stage member 410 are made tocorrespond to the stage member suction holes 451. The suction device 432for the stage member is activated to adhere and hold the stage member410, via the member 450, to the placing face 421 a of the heater part421 by performing a suction operation. Then, after the suction device431 for the circuit board is activated, the FPC 405 is placed onto thecircuit board placing face 410 a of the stage member 410, and the FPC405 is adhered and fixed to the circuit board placing face 410 a via thesubstrate suction holes 411 and the suction grooves 412 of the stagemember 410.

A heating operation performed by the heater part 421 is controlled bythe controller 480 in accordance with the above-referred temperatureprofile. The solder paste 8 is melted by the heating operation, andelectronic components 6 are bonded onto the FPC 405.

At this time, fumes generated from the solder paste 8 are sometimessucked through the through holes 404 of the FPC 405. However, the suckedfumes are discharged through the substrate suction holes 411 and thesuction grooves 412 of the stage member 110, and are therefore preventedfrom contaminating the heater part 421. According to the bonder 401 ofthe third embodiment as above, cleaning the heater part 421 iseliminated and a high productivity can be achieved without stoppingequipment for performing cleaning work.

After the components 6 are completely bonded to the FPC 405 in themanner as described above, operation of the suction device 431 isstopped to stop the suction, and the FPC 405 is removed from the stagemember 410.

Similar to the earlier discussed case of the bonder 101, in the bonder401, the stage member 410 has a size nearly equal to or slightly largerthan the size of the FPC 405 so that one FPC 405 can be placed onto thecircuit board placing face 410 a of the stage member 410. However, thesize of the circuit board relative to the stage member 410 is notlimited to the example of this embodiment, and for instance, a pluralityof bonders 401 may be arranged as is described with reference to FIG. 8so as to place one circuit board on a plurality of stage members 410.

Although the present invention has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

1. A method for bonding electronic components, comprising: placing ontoa stage member so as to be in contact therewith, a circuit board havingelectronic components to be bonded thereto by a bonding material mountedto said circuit board: sucking and holding said circuit board to saidstage member; sucking and holding said stage member to a heating devicevia a space; using said heating device to heat said stage member whilesaid stage member is sucked and held to said heating device therebyheating said circuit board via said stage member such that, said bondingmaterial melts.
 2. A circuit board having electronic components bondedthereto, via a bonding material, by performing an electronic componentbonding method comprising: placing the circuit board onto a stage memberso as to be in contact therewith; and heating said circuit board,thereby melting the bonding material that is to bond the electroniccomponents to said circuit board.
 3. An electronic component mountingapparatus comprising: a bonder for an electronic component, said bonderincluding (i) a stage member for having placed thereon a circuit boardto have electronic components mounted thereto, and (ii) a heating devicefor heating said stage member so as to heat the circuit board while heldin contact with said stage member, and thereby melt a bonding materialthat is to bond the electronic components to the circuit board.
 4. Anelectronic component mounting apparatus comprising: a bonder for anelectronic component, said bonder including (i) a plurality of stagemembers for having placed thereon a circuit board to have electroniccomponents mounted thereto, and (ii) a heating device provided for eachof said stage members for heating said each of said stage members so asto heat the circuit board while held in contact with said plurality ofstage members, and thereby melt a bonding material that is to bond theelectronic components to the circuit board.
 5. The method according toclaim 1, wherein heating said circuit board includes changing a heatingtemperature with respect to a heating time.
 6. The method according toclaim 1, further comprising: after heating said circuit board, coolingsaid circuit board.
 7. The method according to claim 1, wherein suckingand holding said circuit board and sucking and holding said stage memberincludes first sucking and holding said stage member and thenindependently sucking and holding said circuit board.